Poland is saying "not so fast", and is not willing to acknowledge any special greater equity in such population weighted voting, given the way population differences came about in Europe. It is saying "keep one vote per state", knowing full well it underweights the bigger countries. It is saying they should be underweighted in population terms, that they should regard and treat smaller states as their equals, not as junior or second class members of the EU.
Poland is itself a middling country by EU standards. The little ones that benefit the most by one country, one vote are the lowland countries, scandanavia, and the smaller eastern European countries (Poland is much larger than the others in eastern Europe, in population terms).
Thanks for that perspective!